How can the Chi_b (3P) particle exist if matter and anti-matter annihilate?

In summary, the recently discovered Chi_b (3P) is an onium state made up of a bottom quark and an anti bottom quark. It is one of the various bottomonium states, similar to how a positronium state involves an electron and positron orbiting each other. Annihilation between particles and their corresponding anti-particles can occur if they fall out of their allowed orbital energy states. However, this is usually only transient and depends on the particles' charges. Neutrinos and antineutrinos cannot annihilate because they do not have the energy to produce the required gauge bosons.
  • #1
feyomi
4
0
The recently discovered Chi_b (3P) is made up of a bottom quark and an anti bottom quark.
I thought, however, that should a matter particle meet with its anti counterpart, they would annihilate into pure energy.

Am I missing something?

Thanks.
 
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  • #2
The components of a chib(3P) are orbiting around each other - the 3P denotes the orbital quantum state.

Yes, particles and their corresponding anti-particles will annihilate one another if they meet 'directly', but it's also possible for them to form into bound orbital states, even though this is usually only transiently. These states are generally termed '-onium' states. For example positronium states involve an electron and positron orbiting one another, charmonium states have c and cbar components, and the chib(3P) is itself one of the various bottomonium states. The π0 itself is also an onium state, albeit a mixture of u-ubar and d-dbar, and similarly for various other neutral mesons.

Like a Hydrogen atom, each onium group has a set of allowed orbital energy states. To annihilate, the particles must basically fall out of these orbits.

The other caveat about annihilation that doesn't get mentioned much is that, at energies below the electroweak symmetry breaking scale, the particle and antiparticle involved must be either electrically or colour-charged. The products of the annihilation are the corresponding gauge bosons, ie photons and gluons* - annihilation itself is a straightforward interaction between charged particles and gauge bosons. Because the latter are massless, any particle/antiparticle pair with the corresponding charges can transform into them as there will always be a state of two or three real gauge bosons that has lower energy than that of the particle + antiparticle. Neutrinos and antineutrinos, however, can't do this, because they only carry weak isospin charges and so the only gauge bosons they could interact with, and hence annihilate into, are Ws and Zs, which are very heavy. The cosmic neutrino background contains both neutrinos and antinuetrinos (assuming neutrinos are Dirac particles and not Majorana) but these can't annihilate because they don't have the energy to produce real Ws or Zs.

* sufficiently energetic pairs can also annihilate into single virtual gauge bosons that then produce new, lighter particle pairs eg e+e-.
 
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  • #3
PS to clarify the last point a bit more, a neutrino-antineutrino pair can produce a virtual Z0, but the only thing the latter can then do is produce another neutrino-antineutrino pair, because neutrinos are the lightest particles that interact with Z0s.
 
  • #4
Cool, thanks Adrian.
 

1. How can matter and anti-matter annihilate if the Chi_b (3P) particle exists?

The existence of the Chi_b (3P) particle does not contradict the principle of matter and anti-matter annihilation. This particle is a subatomic particle that can be created in high-energy collisions, but it is unstable and quickly decays into other particles, including matter and anti-matter particles. Therefore, the existence of the Chi_b (3P) particle does not violate the conservation of energy and the principle of matter and anti-matter annihilation.

2. Is the Chi_b (3P) particle a form of anti-matter?

No, the Chi_b (3P) particle is not considered a form of anti-matter. It is a subatomic particle that is composed of quarks, just like protons and neutrons. Anti-matter particles have the same mass as their matter counterparts, but they have opposite charge. The Chi_b (3P) particle does not have an opposite charge and therefore, it is not considered a form of anti-matter.

3. What is unique about the Chi_b (3P) particle?

The Chi_b (3P) particle is unique because it is a meson with a bottom quark and a bottom anti-quark. It is also unique because it is in a "P-wave" state, which means that the quarks' spins are aligned in a parallel direction. This gives the Chi_b (3P) particle a higher energy state compared to other bottom mesons, making it more difficult to create and detect in experiments.

4. How is the existence of the Chi_b (3P) particle confirmed?

The existence of the Chi_b (3P) particle was first predicted by theoretical models in the 1970s. It was later confirmed in experiments at the Large Hadron Collider (LHC) in 2011, where it was observed as a peak in the distribution of particles produced from proton-proton collisions. The observation of this particle provides further evidence for the validity of the Standard Model of particle physics.

5. What is the significance of the Chi_b (3P) particle?

The discovery of the Chi_b (3P) particle has significant implications for our understanding of the fundamental building blocks of matter. It helps to validate the Standard Model of particle physics and provides insights into the strong nuclear force, which is responsible for holding quarks together to form particles. The study of this particle also contributes to our understanding of the early universe and the conditions that existed shortly after the Big Bang.

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